Great idea. Voila: https://igraph.discourse.group/t/modularity-q-based-on-the-louvain-split-unexpected-values/159
Makis On 29 Mar 2020, at 15:14, Szabolcs Horvát <[email protected]<mailto:[email protected]>> wrote: I would recommend posting the question on https://igraph.discourse.group/ as that forum is meant to replace this mailing list, and provides a nicer discussion environment. On Sun, 29 Mar 2020 at 15:08, serafim loukas <[email protected]<mailto:[email protected]>> wrote: Just to add that I just found the python version of BCT (the Matlab toolbox that I used to benchmark igraph). Using this: https://github.com/aestrivex/bctpy/blob/f9526a693a9af57051762442d8490dcdf2ebf4e3/bct/algorithms/modularity.py#L71, again I get approx. 0.1466 that matches the Matlab based results but is far from the python output (Q). Makis On 29 Mar 2020, at 14:56, serafim loukas <[email protected]<mailto:[email protected]>> wrote: Hi igraph community, I have a graph and I want to estimate the modularity (Q) based on the Louvain split of the graph. In python I used igraph and to compare, I also estimated Q in Matlab. Based on igraph, the Q is negative (weird) whereas the Q based on the Matlab estimation is possitive. I would expect differences in the values but not by so far (+ shows modularity, - shows anti-modularity). Any idea why this happens? Makis ——————————— My code and data: PYTHON ``` import numpy as np import scipy.io<http://scipy.io/> from igraph import * A = scipy.io.loadmat('A.mat')['A'] graph = Graph.Weighted_Adjacency(A.tolist(), mode=ADJ_UNDIRECTED, attr="weight", loops=False) Louvain = graph.community_multilevel(weights=graph.es<http://graph.es/>['weight'], return_levels=False) Q = graph.modularity(Louvain) print(Q) -0.001847596203445795 ``` MATLAB (https://sites.google.com/site/bctnet/measures/list) using community_louvain.m: Louvain community detection algorithm ``` clear all load('A.mat') [M,Q]=community_louvain(A); Q = 0.1466 ``` <A.mat>_______________________________________________ igraph-help mailing list [email protected]<mailto:[email protected]> https://lists.nongnu.org/mailman/listinfo/igraph-help _______________________________________________ igraph-help mailing list [email protected]<mailto:[email protected]> https://lists.nongnu.org/mailman/listinfo/igraph-help _______________________________________________ igraph-help mailing list [email protected]<mailto:[email protected]> https://lists.nongnu.org/mailman/listinfo/igraph-help
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